I have done a write-up on how to switch out the ring and pinion in a Ford 9.75 rear end.

I am not qualified to do this write up however I did mine and it wasn't too hard. I haven't had any problems after 15K on my new gears. And it seems to be a lot of interest in this topic so this is better than nothing.

I don't claim to be an expert so if anyone has any improvements or comments please let me know.

This can be a work in progress!

 

Instructions for switching gears in a Ford 9.75” rear end
These instructions may not be complete-----Use these instructions at your own risk!!!!!!!!!
I am not a professional. I have only done this twice in my life but I have been running my 4:88s for about 15K miles now with no problems.
I am doing this from memory so be aware. Plus some bolt sizes I reference will be wrong.
Do not blame me if you screw up your truck!!!!!!!!!!!

Also attached are the instructions that come with Yukon Gears. This will give you some info that I left out like checking the pattern, etc.

1. Remove cover. This can be more difficult than you would think. The OEM gasket maker is VERY strong and you want to be very careful so you don’t damage/bend the cover otherwise it will be hard to get to seal up when you put it back on.

I found that the best thing to use is a 1-1.5inch putty knife. Jam that behind the cover and use a hammer to move it around the cover and cut the gasket until you can pull off the cover. (cuss as the rear end fluid splashes all over you and your floor) Clean up everything as good as possible. Inside the housing and outside on the floor and such.

2. Remove tires, brake calipers, and rotors.

3. If you look in the middle of the differential you will see a steel shaft that is between the two axles coming from both sides. This must be removed so you can get the “C clips” off the axles and slide out the axles. There is a 10mm or so bolt that is on one end of this shaft that must be removed. Then the steel shaft will slide out of the differential. Reference pic for some help.

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4. Now with the shaft out you can push the axles in a little so that the “C clip” can be removed off of the axle. You have to get the axle moved in as far as possible so the clip can be removed. Turning the axle one way or another a little will help it move in more.

 

5. With the C clips removed. Slide the axle out some so it is clear of the differential.

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6. Ok now that the axles aren’t holding in the differential you can remove the Carrier Clamps. There are two 17mm or so bolts on each one. Remove these and set them aside. SEE ABOVE PIC. SET ALL PARTS ASIDE EXACTLY AS THEY WERE IN THE REAR END. YOU WILL WANT TO PUT EVERYTHING BACK EXACTLY AS IT WAS LATER. As you pull off the carrier clamps notice which side of each clamp is the inside and which is the outside. These hold in the axle bearings so you don’t want to screw this up.

7. Ok now that the clamps are off there is nothing holding in the differential now. However it is still jammed in there pretty tight. Hopefully not too tight! I used two large pry bars. One on the top and one on the bottom to get the differential out of the housing. Pry on the ring that you will be replacing so if it gets scratched it’s no big deal. BE SURE THAT YOU DON’T DAMAGE ANYTHING DOING THIS! YOU COULD POSSIBLY DAMAGE THE HOUSING, BEARINGS, OR THE DIFFERENTIAL IF YOU PRY TOO HARD! Mine came out pretty easy. But I guess sometimes it is necessary to use a housing splitter. This is some kind of device that pries the housing apart to make it easier. I didn’t need one so I can’t help ya there. Also pay attention to how everything is in place as you pull the differential out. The spacers and races may fall out so be sure to catch them so they aren’t damaged and you know how to put it back together again.

8. Ok now the differential is out. Clean it up and set it aside. Lets get out the pinion.

9. To do that you will have to drop the drive shaft. There are 4 12-point bolts that hold the drive shaft to the pinion. Somewhere around 12mm or so. These are a bit of a pain in the a** because the shaft can now spin freely and there also isn’t much room to work around these bolts. I used a 3 ft pry bar and placed it between couple of the bolts and the floor to hold it while I removed the other bolts. An impact would be nice here if you have one.

10. Ok now with the drive shaft down you can see the pinion nut that will need to be removed. I’m thinking that it is a 1 1/16" nut. Again an impact would be great here if you have one. I didn’t have air at the time so I put the drive shaft bolts back in and used them with the pry bar to hold the pinion in place to remove the nut. Keep this process in mind for when you have to reinstall the pinion.

11. Ok now you got the pinion nut off. The pinion will have an indention on the end of it where you can put a large punch. Stick it in there and drive out the pinion toward the back of the truck. You will need a pretty big hammer.

 

12. Ok now the pinion should be out and you will have something like this.

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13. Now you need to pull off the bearing so you can get the shim that is underneath of it.
To do this you will probably need a press.

14. Once you have the shim. Slide it over your new pinion and press the new bearing onto the pinion. Finally slide the NEW crush sleeve on. IT MUST BE A NEW CRUSH SLEEVE!
15. Ok now it’s time to get the old pinion race out of the housing. This can be a pain in the a**. I used a punch and drove it out from the front of the vehicle. Be careful not to damage the housing when you’re doing this! It’s pretty hard to see where the race starts and the housing ends so all I can say is be careful and make sure you look at it good with a light. It is in there pretty tight so it will take some beating to get it out. DON’T BLAME ME IF YOU F UP SOMETHING. Really its not that bad just take your time.

Slide2.jpg?t=1216157918

16. If you look at this pic you will also see another bearing towards the drive shaft side of the housing. I you may want to inspect this and see what you think. I didn’t change mine. It had about 40K on it.
17. Ok I’m assuming you have cleaned everything up by now and your ready to start putting this back together!
18. Ok time to put the new pinion bearing race into the housing. Do this the opposite that the old one came out. Except be very careful not to jack it up!!! Instead of a punch, use a hard piece of wood or plastic or something to punch it in. Lube it up a bit with some gear oil first.
19. Ok that’s done. That was easy. Now put in the new pinion with the new bearing. Hope you stuck the spacer under the bearing before you pressed it on! Ok just slide it in from the back and get it thru far enough so that you can get the nut back on the front side. USE LOCKTITE! Oh yea don’t forget the housing that the drive shaft bolts too. Line up the splines and slide it together.
20. Ok now you have the nut started. This is where a little finesse is involved. What you have to do is tighten this pinion nut tight enough to preload the bearing. You will want to keep tightening the nut until the pinion has about 15-19 ft-lbs of torque on it when you turn it in the housing. (15-19 ft lbs is for a 9.75 ford read end using a new bearing. You should be able to find specific tolerances with your instructions or call Ford or something.) One way to check this is with one of those old torque wrenches that has a bar and dial on it. I had some help from my mechanic buddy the first time I did this. I can’t really explain what 15-19 ft lbs feels like so I am going to have to leave that up to you to figure out.
21. Ok the new pinion is back in! Time to get the ring installed and back in.
22. Unbolt the ring bolts and you should be able to get the ring off without a press. I stick two bolts back in and backed them off about 1/8 inch and hit them with a hammer until the ring started moving off the differential. Then back them off some more until it gets easy to get off. Be careful so you don’t jack up the threads on the bolts!
23. Now you can put the new ring on the differential. It was cold when I did this so I stuck the ring on the wood stove and the differential outside in the 20 degree weather for a while. Then I was able to get it on good enough to get the bolts started and then I just slowly turned all the bolts in the same fashion as you tighten the lug nuts on a wheel. Be careful so you don’t get it in a bind. If you heat the ring and cool the differential enough you could probably use a mallet to hit it on once you get a few bolts in to ensure that it’s lined up. USE LOCKTITE!

 

24. Ok now properly torque the ring bolts. This is VERY important to get correct. I’ll leave it up to you to get the specs for your own vehicle.

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25. Ok now it’s time to put all this back into the housing. This can also be difficult if it was real tight getting out. Now is also a good time to check the other bearings and make sure they seem ok. If they seem worn replace them. Mine were fine so I didn’t.
26. Stick the races back on and maybe one spacer and slide the whole thing back into the rear end housing. The spacers are kind of brittle so be careful here. Use the wooden handle of a hammer and try to get the differential back in with the spacers in pace so you can slide the axles back in. I don’t really know what to tell ya here. Just get it in there and be careful so you don’t break the spacers.
27. Ok so now you got it back in. Slide in one of the axles and put back on the C clip. Then do the same with the other side. Then put the shaft back in and stick the bolt in. LOCKTITE!!!!
28. Note: My 4:88 ring was so wide that it blocked the shaft from going in straight so I couldn’t get it back in. If you run into this here is what I did. It was VERY VERY close to sliding in but needed just a bit more clearance. I grinded one tooth down on the ring with a dremel tool with a drum sanding attachment on it. I’m not sure if that was good or not but I don’t see a problem with it. And everything is good now 15K later.
29. Ok now that everything is back together it’s time to check the tolerances and hope that they are OK so you don’t have to do this all over again and find some new spacers and such.
30. First get out the Dial Caliper and check the backlash. The instructions that came with the gears should have the specs with them. Basically the backlash is the play that the ring and pinion have between them. Actually I think the backlash was a bit loose on mine. It was supposed to be 6-10 but mine came in at 11. But when I checked the pattern it was good so I went with it.
31. Checking the pattern: Get some gear-marking compound from your local auto parts store.
32. Ok I’m not going to go into what a good pattern looks like. Your instructions should explain this in enough detail for ya.
33. Ok if your pattern isn’t good and your backlash is off, you must change some spacers and I didn’t have to do that so that sucks for you. My rear end pattern came out almost perfect but the front wasn’t perfect. Just think about how much you actually use your 4x4 and see if you think it’s bad enough to warrant trying to get it better.
34. Ok let’s say your patterns are good. Now use some BLACK high temp RTV gasket maker and put your cover back on. Don’t over tighten the cover bolts. I think this is what I kept doing and I as squishing all the gasket maker out and that ‘s why I had trouble getting it to quit leaking.
35. I would suggest that u put the cover back on and let it set overnight or something so the gasket maker can set up. However my Mechanic buddy said that they always stick the fluid in right away and they have no problems so it’s up to you.
36. You must use synthetic 75-140 gear oil in these trucks! Double check with your auto parts dealer to make sure your buying the right stuff. IT”S FLIPPIN EXPENSIVE I KNOW THAT! Also be sure to add the friction modifier. You can buy that from FORD.
37. Ok fill it up to the fill hole and give er hell! Actually you should have a break-in procedure with your gears instructions that you should follow.
38. When you first take off down the road listen for gear noise. I’m pretty sure I didn’t have any but it would have been hard to hear over the tire noise of my 35” Claws and exhaust anyway!
39. If they do make noise it think that means they are too tight.


The front end is pretty much the same as the rear except you will need to take the entire differential out of the truck and do all the work on a bench. Also there is some 4x4 locking stuff in there. Just be careful taking it apart and put it back the way you took it apart!

 

I Vote Sticky!!!!!!

 

Here is the link to Yukon's instructions. It will give needed info regards to checking the pattern and a bunch of other info also.

http://www.yukongear.com/Downloads.aspx

 

I just checked an old pinion nut I had. You need a 1 1/8 deep wall socket to fit it.

 

X-2 Great Job efuehrin

 

Here is another excellent article: http://www.pirate4x4.com/tech/billavista/Gear_Setup/

 

Great find minimonster17!

That should cover most of what I missed.

 

Ya between the two threas I think it has been covered pretty well.

 

Hey guys just wondering here.

My truck cruising at 60ish is pulling 1700rpms and around 65ish 1800-1900rpms

what do yall think my rpms will be after 4.56's and 4.88's

 

what size tires do you have now and what gear ratio do you have?

 

36" tires 3:55 gears.